Spatiotemporal patterns of fish chorusing in California National Marine Sanctuaries

In aggregations, some male fish will sing together in “chorus” for hours, to attract female mates. Through analyzing passive acoustic data, one can determine which, when, and where fish are chorusing, to identify breeding grounds, species distributions, and mating seasons. National marine sanctuaries aim to protect marine ecosystems, particularly breeding and feeding grounds for at risk species. Through the Sanctuary Soundscape Monitoring project, a cumulative 17.9 years of passive acoustic data were manually analyzed for fish chorusing in Monterey Bay, Channel Islands, and proposed Chumash Heritage National Marine Sanctuaries. We aimed to determine which fish were chorusing within the sanctuaries, where and when they occurred, and if fish were engaging in acoustic niche partitioning (minimizing overlap in time/frequency to reduce competition). We found five unique fish choruses including plainfin midshipman, bocaccio rockfish, white seabass, and two unidentified fish choruses, which showed distinct diel, seasonal, and spatial preferences. Fish were found to partition acoustic space in frequency but not in time. Understanding fish reproductive habitat and behavior within sanctuaries is crucial for safeguarding threatened fish species. Moreover, studying fish chorusing is a powerful tool to noninvasively monitor fish to understand their reproductive habits, with goals of better protecting them.